US Army bans USB devices to contain worm

Unfriendly fire

The US Army has reportedly suspended the use of USB and removable media devices after a worm began spreading across its network.

Use of USB drives, floppy discs, CDs, external drives, flash media cards and all other removable media devices has been placed on hold in order to contain the spread of Agent-BTZ, a variant of the SillyFDC worm, Wiredreports. Such a temporary ban would cause inconvenience in any organisation, but for the US military it's an even more serious problem because in many locations email or online transfer of files are not viable options.

The clampdown applies to both the the secret SIPR and unclassified NIPR networks, according to internal Army emails cited by Wired. Variants of the the SillyFDC worm are capable of spreading over networks or removable media devices, infecting any Windows PC they are plugged into or any external drive connected to an infected device, for example. The malware is programmed to download secondary infectious code from the internet, establishing a conduit that might be used to download keylogging software, password-siphoning spyware or botnet agents onto compromised machines.

Army top brass are using the suspension to clamp down on the use of personally-owned or otherwise unauthorised devices on US military PCs. Government-approved drives will reportedly be allowed back onto the network soon, but not before they've been scanned and cleared of malware infection. Government security teams will be running custom scripts and daily scans for the dual purposes of making sure the ban is enforced and detecting the spread of other forms of malware, Wired adds.

The ban, which gets in the way of troops' normal work, might seem like over-kill, but without knowing the full specifics of the extent of the infection it's probably a little unfair to label it as such.

However, security experts say that actions short of an outright ban may be appropriate for organisations facing similar problems.

"We would advise that users disable the autorun facility of Windows so removable devices such as USB keys and CD ROMs do not automatically launch when they are attached to a PC," explained Graham Cluley, senior technology consultant at Sophos.

"Any storage device which is attached to a computer should be checked for virus and other malware before use. Floppy disks, CD ROMs, USB keys, external hard drives and other devices are all capable of carrying malicious code which could infect the computers of innocent users. Companies can also use technology to help prevent staff from accessing unauthorised devices like USB drives," he added. ®